Troublesome protozoan infection common among Palestinian livestock – study

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Trypanosoma evansi in blood.
Trypanosoma evansi in blood. © Mohamed Ridha Rjeibi, Taoufik Ben Hamida, Zara Dalgatova, Tarek Mahjoub, Ahmed Rejeb, Walid Dridi and Mohamed Gharbi [CC BY (https://creativecommons.org/licenses/by/4.0)]
Researchers have found evidence of high levels of a troublesome protozoan infection among livestock, including horses, in Palestine.

Suheir Ereqat and her colleagues used molecular-based methods and microscopic examination of blood smears to assess the prevalence of Trypanosoma evansi, a protozoan which causes surra, also known as trypanosomiasis.

Surra is a disease that can affect many animals. It can cause fever, weakness and lethargy, which lead to weight loss and anemia. The disease can be fatal in some animals unless treated with chemotherapy.

It is hypothesized that T. evansi initially developed in camels and has since spread to many domestic and wild mammals. Blood-drinking horseflies seem to play an important role in its transmission.

The infection has been reported in 48 countries around the world.

For the study, the researchers collected blood samples from camel herds in the West Bank and Gaza Strip from eight districts — Ariha (Jericho), Nablus, Bethlehem, Deir Al Balah, Jenin, Rafah, Tubas, and Khan Yunis.

In addition, horses, mules, donkeys, goats and sheep that were close to the camel herds were also sampled.

In all, 259 blood samples were obtained from a range of livestock species, comprising 87 camels, 46 horses, 28 donkeys, 2 mules, 49 sheep and 48 goats.

The overall infection prevalence was found to be 18% — 46 of the 259 animals.

The positivity rates according to molecular-based testing was 17% while microscopy examination was 2.7%.

The infection rates were: camels, 26/61 (30%); horses, 8/46 (17%); donkeys, 3/28 (11%); mules, 1/2 (50%); sheep, 2/42 (4%); and goats, 6/42 (13%).

They found that sex and age group were not significant risk factors for infection.

“To the best of our knowledge, this is the first confirmation of high levels of infection with T. evansi as a causative agent of surra in Palestine,” the study team reported in the journal Parasites & Vectors.

The authors noted that, in Palestine, about 730,000 sheep, 215,000 goats, 1500 camels and 3600 equines are being raised, mainly in the districts of Al-Khalil and Ariha.

These numbers are considered relatively low compared to those in Middle East countries, such as Saudi Arabia, Jordan and Iraq.

In Palestine, the overall trypanosomiasis prevalence detected was similar to the infection rate of neighboring countries in the region, they said.

“Our study emphasizes the need for a stringent surveillance system and risk assessment studies as prerequisites for control measures,” they said. “Further investigations focusing on vectors and evaluation of risk factors are needed.”

The greatest prevalence was around Jenin, Tubas and Ariha (Jericho), suggesting these areas should be targeted first.

The study team comprised Ereqat, Abdelmajeed Nasereddin, Amer Al-Jawabreh, Hanan Al-Jawabreh, Nahed Al-Laham and Ziad Abdeen, from a range of Palestinian institutions, including Al-Quds University, the Al-Quds Public Health Society, the Arab American University and Al-Azhar University-Gaza.

Ereqat, S., Nasereddin, A., Al-Jawabreh, A. et al. Prevalence of Trypanosoma evansi in livestock in Palestine. Parasites Vectors 13, 21 (2020) https://doi.org/10.1186/s13071-020-3894-9

The study, published under a Creative Commons License, can be read here.

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